The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some of such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.
The evolvement of communication technology, particularly IP-based (IP, Internet Protocol) communication technology and end user terminals, has enabled versatile communication possibilities, including a mobile IP with mobile networks. The Internet edge mobility allows a host, such as a mobile portable IP-enabled device, to change its point of attachment to the Internet but still be identifiable through the same IP address. A mobile network is a subnet that can change its point of attachment to the routing infrastructure. The mobility of a network is provided by a mobile router, which provides connectivity and reachability as well as session continuity for all the nodes in the mobile network behind the mobile router, the nodes being either hosts or other mobile routers forming a nested network. This mechanism is called network mobility (NEMO). In NEMO, instead of assigning single IP addresses to single nodes, one or more IP prefixes are assigned to a mobile router. This allows a subnet behind the mobile router and a group of hosts attached to the subnet to be identifiable through the same IP prefix. (An IP prefix defines a set of IP addresses and in IPv4 the prefix may also be called a network address.) The mobile router typically serves as a default gateway for the hosts on the mobile network and the mobile router needs to register and update its point of attachment to its home agent so that the home agent will be aware of the network behind the mobile router and the associated IP prefixes. This signaling establishes a bi-directional tunnel between the home agent and the mobile router, the tunnel making the network movements transparent to the mobile nodes behind the mobile router and ensuring that traffic sent to the host's IP address will arrive at the intended node.
For route propagation, the home agent advertises mobile networks known by the home agent to other mobile routers. For example, during registration, a joining mobile router may request information on route optimizable networks from the home agent and may receive in a registration response zero or more prefix advertisements extensions, the extensions informing the mobile router on all known existing registered mobile networks and the mobile routers that manage them. If hundreds of mobile routers share the same home agent, transmitting prefixes in a corresponding number of extensions, consumes bandwidth since each prefix requires a separate extension.